Bottom bracket/crankset dilemma

[Chuffy]

Chaps, I have a dilemma. Luther, my Sunday best bike (Guess SC1, weighs 8kg in his socks, very whizzy and fast) has a knacked BB. Sounds like the bearings are breaking up. He has an ISIS BB and apparently this isn’t uncommon. So, I have a number of possible options but I can’t decide what to do. Any words of wisdom?

1. Replace shagged BB with a nicer ISIS BB.
2. Replace entire crankset and BB with nice shiny Shimano setup (Ultegra perhaps?)
3. I’ve got an offer of a free Stronglight Mygal chainset. Which would mean replacing the BB with a trad square taper.

Option 1 carries the obvious caveat that it will probably happen again, but means I can keep using the crankset, which is perfectly ok and won’t work on any of my other bikes.

Option 2 would be nice, but very expensive.

Option three sounds good but is square taper a bit old skool for a superlight whizzy road bike? Wouldn’t a new Ultegra setup be much stiffer, faster and more reliable?

Have I missed an obvious Option 4 somewhere?
Cheers,
Chuffy

 

[djb1971]

go for option 2 with a new hollowtech bb. As you say a little bit extra but worth it in the end, plus the bb will be dead easy to replace next time and you can get a 105 bb for a tenner. They are better than isis too

 

[djb1971]

That's what I did

[ATTACH=full]163263[/ATTACH]

 

[Tim Bennet.]

ISIS bottom brackets (and to a slightly lesser degree - Octolink) were a triumph of marketing over substance. In order to make the axles larger diameter, the bearings had to be reduced to the size of pin heads and their durability nose dived.

There are now some better engineered ones, including SKF, which have seen their life expectancy rise from a couple of hours mountainbiking to over a year (so far). So one of these would probably work well on a road bike for quite some time.

However, there was nothing, and still is nothing wrong with square taper. The only problem was people doing huge drops on mtbs and landing with all their weight on the pedals. This was the trigger for the development of the Octolink / ISIS ones, but all the talk of increased stiffness necessary for road riding was just a way to try and force some standardisation across the board. But while Shimano were wittering on about their latest innovation to solve this non problem, Tom Boonen was out sprinting everyone without any perceptible disadvantage using a square taper Campag set up.

The external bearing BB are just a response to Shimano making a complete cock up of the engineering of their Octolink and everyone else jumping on the bandwagon with ISIS. If there was really no need to replace square taper on road bikes, don't get to suckered for how 'necessary' the second generation replacement really is.

 

[Crackle]

Are you going to want to change the chainring combinations? If so, Stonglight, if not, Isis if skint, Hollowtech if plush (Ultegra looks nice though).

 

[yenrod]

ISIS bottom brackets (and to a slightly lesser degree - Octolink) were a triumph of marketing over substance. In order to make the axles larger diameter, the bearings had to be reduced to the size of pin heads and their durability nose dived.

There are now some better engineered ones, including SKF, which have seen their life expectancy rise from a couple of hours mountainbiking to over a year (so far). So one of these would probably work well on a road bike for quite some time.

However, there was nothing, and still is nothing wrong with square taper. The only problem was people doing huge drops on mtbs and landing with all their weight on the pedals. This was the trigger for the development of the Octolink / ISIS ones, but all the talk of increased stiffness necessary for road riding was just a way to try and force some standardisation across the board. But while Shimano were wittering on about their latest innovation to solve this non problem, Tom Boonen was out sprinting everyone without any perceptible disadvantage using a square taper Campag set up.

The external bearing BB are just a response to Shimano making a complete cock up of the engineering of their Octolink and everyone else jumping on the bandwagon with ISIS. If there was really no need to replace square taper on road bikes, don't get to suckered for how 'necessary' the second generation replacement really is.

I still ride a square taper BB.

I did notice the cranks on MTB cranks could suffer a bit of 'bending'.

So instead of 180' - it'd be 175'-180'.

I have rode Octalink (italian - god knows if that makes any difference) and I wasn't too plussed with the amount of space on the axle for the crank.

Then you used a 8mm allen key to put them on.

But you couldnt just use your hand - you'd have to use a spanner, a 8" adjustable or such like to get them tight enough.

Wasn't at all, impressed by them.

Not sure on the ISIS BB's but I'd like to see if they are any good!

I am thinking of acquiring a Richey C.Set for 40 £ squre taper with one of the arms on the back of the crank arms, as the Shimano BB for the no-name c.set (ive got) - sets the distance/spacing from the chainstays.

 

[ghitchen]

How about option 3 but with a Royce Titanium axle?

http://www.genisysconsulting.co.uk/royce-uk/

 

[fossyant]

OR a Dura Ace / XTR square taper BB......

Cheapest option is to get a good quality ISIS type BB !

 

[djb1971]

I was in the exact same position as you chuffy and I had already gone through 3 isis BB's. They suck a big one !!!

Go square taper for the best cheaper option or pay more ££ and get a more modern hollowtech to go with the bike. I went ultegra because everything else on the bike is also ultegra and it was only around £100 with an ultegra sl bb and compact chainset. They are super easy to install and remove for maintenance etc. and they suit a modern speed machine


and my vanity

If you don't want compact they're even cheaper as standard

 

[Chuffy]

Decisions, decisions.....

Thanks chaps. It's tricky because I don't like the thought of just making a perfectly decent crankset (Truvativ Rouleur) redundant because I've changed BB. Square taper sounds like a sensible option, perhaps with a nice BB like one of these. Yes, I have considered Royce but they are damn expensive. I think I'll ditch the Ultegra option. Mainly because of the cost, but also because I can't figure out how they work...

I'll see how nice the freeby crankset is and decide then...

 

[Tim Bennet.]

If there's plenty of life left in your Truvativ ISIS chainset and rings, then a new SKF bottom bracket will be worth the expense. The SKF model (350?) for less than forty quid is well engineered. The only difference with the model costing twice as much is that one is it's made entirely stainless steel, but I'm not sure if it's more durable.

Be careful of the TA bottom brackets. They have traded durability for lightness. You also have to be careful of getting your tapers matching; the two 'standards' are JIS and ISO. For reliability (and I say this with as much ease as a cat bringing up a hairball), there is nothing wrong with the square taper ones from . . . Shimano.